1. Field of the Invention
The present invention relates to an air pump and, especially, to an air pump that supplies air automatically.
2. Description of the Prior Art(s)
Air pumps are critical to all kinds of inflatable articles, such as airbeds, inflatable bouncers, inflatable sofas, inflatable toys, and the like. The air pump is mounted on an inner surface of the inflatable article, inflates the inflatable article and holds air inside the inflatable article at a constant pressure for use, and deflates the inflatable article for storage. Currently, some conventional air pumps can inflate and deflate the inflatable articles, and hold the air inside the inflatable articles at a constant pressure. Meanwhile, other conventional air pumps further have auto-stop controllers that stop the air pumps automatically. The auto-stop controller is mounted in a housing of the conventional air pump, and has a sensing film, a micro switch, a driving rod, a button, and a compression spring. The button is operated in a single stage, so that when the button is pressed, the driving rod is driven to move upwardly to push the sensing film. Accordingly, the sensing film deforms upward to switch the micro switch on. When the button is released, the compression spring pushes the driving rod to move downwardly. Accordingly, the sensing film deforms downward to switch the micro switch off. The micro switch controls an operation of the conventional air pump. Moreover, the conventional air pump may further have a main switch. The main switch independently controls the conventional air pump. To operate the conventional air pump, the main switch must be first switched on.
The auto-stop controller allows the conventional air pump to stop working automatically, which is a great convenience to users. However, performance of the conventional air pump is still inadequate to achieve a best usage effect and a best working performance. The shortcomings of the conventional air pump are described as follows. The conventional air pump only stops working automatically, but does not supply air to the inflatable article automatically. Thus, when the inflatable article is deflated, the micro switch should be manually switched on in order to supply the air to the inflatable article. Furthermore, since the conventional air pump can only inflate the inflatable article to a specific hardness, the hardness of the inflatable article cannot be adjusted according to the user's need. Thus, the conventional air pump is inconvenient for use and operation.
To overcome the shortcomings, the present invention provides an air pump capable of automatic air supplement to mitigate or obviate the aforementioned problems.